Hvac system of an automotive vehicle and method of operating the same

ABSTRACT

A climate control system for the interior cabin of an automotive vehicle. The climate control system includes a mode selection device configured for selecting a defrost mode. When the system is in the defrost mode, a controller receives a signal from a humidity sensor indicative of the measured humidity level in the vicinity of the window. The controller compares this measured humidity level with a threshold humidity level and, if the humidity is below the threshold humidity level, the controller stops operation of a compressor being used to dehumidify the air being provided to defrost the window, thereby minimizing possible fogging of the window and increasing the efficiency of the vehicle.

BACKGROUND

1. Field of the Invention

The present invention generally relates to the climate control system of an automotive vehicle. More specifically, the invention relates to a climate control system for preventing the fogging of a window of an automotive vehicle while improving fuel efficiency.

2. Description of Related Art

Generally, the climate control system in an automotive vehicle performs several functions. In addition to generally maintaining the interior cabin temperature of the vehicle, the climate control system can also be used to defrost or defog certain windows of the vehicle.

The exterior of the front windshield of the vehicle is subject to becoming covered with ice. In addition to this, if humidity and temperature conditions are right, frost or fog may either alternatively or simultaneously form on the interior surface of the windshield. Similarly, this fogging on the interior surface may occur on side windows of the vehicle as well. One factor contributing to fogging of the windows of the vehicle is that the climate control system may direct warm humid air onto a cool window surface if the climate control system is in its defrost setting.

To combat the fogging problem, climate control systems have been configured to automatically dehumidify air when the system is in the defrost mode. To dehumidify air being directed toward window surfaces of the vehicle, when the HVAC system is placed into the defrost mode, the compressor of the HVAC system is automatically turned on. Air is then passed over the condenser or heat exchanger coupled to the compressor. The temperature of the condenser causes moisture in the air to condense on the exterior surfaces of the condenser, thus drying the air. The dry air is then heated and directed at the targeted window surface.

The operation of a compressor, however, is a significant source of power consumption in the vehicle, and vehicles can see decreases of 10-20 hp. As a result, operation of the compressor decreases the fuel economy in gasoline, diesel and hybrid vehicles by up to 10% and decreases the mileage range in an electric vehicle.

SUMMARY

In overcoming the enumerated drawbacks and other limitations of the related art, the present invention provides a climate control system for the interior cabin of an automotive vehicle, the climate control system comprising: a mode selection device configured for selecting between a defrost mode and at least one non-defrost mode; a compressor and condenser configured to dehumidify air being provided to an interior cabin of the automotive vehicle; a humidity sensor located adjacent to a window of the automotive vehicle; a controller coupled to the mode input device, the compressor and condenser, and to the humidity sensor; a blower configured to move air over the condenser in providing air to the cabin of the automotive vehicle; and wherein, when the mode selection device is in the defrost mode, the controller being configured to receive a humidity signal from the humidity sensor indicative of the humidity in the vicinity of the window and being configured to operate a compressor if the humidity is above a threshold value and to not operate the compressor if the humidity is below the threshold value.

In another aspect of the invention, the window is a windshield of the automotive vehicle.

In a further aspect of the invention, the window is a side window of the automotive vehicle.

In still another aspect of the invention, two humidity sensors are provided and the controller is configured to operate the compressor if the humidity signal from at least one of the two humidity sensors is greater than the threshold value and is configured to not operate the compressor if the humidity signals from all of the humidity sensors are below the threshold value.

In an additional aspect of the invention, an air vent is located adjacent to the window and coupled to direct air from the blower onto the window.

In a still further aspect of the invention, the humidity sensor is spaced apart from the vent.

In yet another aspect of the invention, the humidity sensor is located adjacent to a lower portion of the window.

In another aspect of the invention, a method of operating a climate control system of an automotive vehicle is provided comprising the steps of: measuring the humidity of air in a vicinity of a window of the automotive vehicle; determining if the climate control system is in a defrost mode; providing a flow of air specifically directed toward the window when the climate control system is in the defrost mode; measuring the humidity of air in the vicinity of the window; comparing the measured humidity with a threshold humidity value; determining if a compressor coupled to a condenser provided as part of an air conditioning subsystem is operating; and if the compressor is operating, turning OFF the compressor when the measured humidity is less than the threshold humidity value.

In a further aspect of the invention, the step of measuring the humidity of air is performed at two locations within the vicinity of the window.

In another aspect of the invention, if the measured humidity at one of the two locations is above the threshold humidity value, the compressor is not turned OFF.

In still another aspect of the invention, if the measured humidity at both of the two locations is below the threshold humidity value, the compressor is turned OFF.

In yet another aspect, the invention further comprises the step of heating the flow of air.

In a further aspect, the invention provides a climate control system for the interior cabin of an automotive vehicle, the climate control system comprising: a defrost mode selection device provided as part of a user interface and being selectable to enter a defrost operational mode of the climate control system; a compressor and a condenser configured to dehumidify a flow of air being provided to an interior cabin of the automotive vehicle, the condenser being located within the flow of air; at least one humidity sensor located adjacent to a window of the automotive vehicle and configured to provide a measured humidity signal indicative of a measured humidity level; a controller coupled to the defrost mode input device, the at least one humidity sensor, and the compressor and condenser; a blower configured to move air over the condenser in providing the flow of air to the cabin of the automotive vehicle; and wherein, when the defrost mode selection device is selected, the controller being configured to receive the measured humidity signal from the at least one humidity sensor and being configured to compare the measured humidity level to a threshold humidity level, wherein the controller is configured to stop operation of the compressor if the measured humidity level is less than the threshold humidity level.

In an additional aspect of the invention, the window is one of a windshield and a side window of the automotive vehicle.

In yet another aspect of the invention, the controller is configured to continue operation of the compressor if the measured humidity level is greater than the threshold humidity level.

In a still further aspect, the invention further comprises a plurality of humidity sensors, the controller being configured to stop operation of the compressor if the measured humidity levels from all of the humidity sensors are less than the threshold humidity level.

In another aspect, the invention further comprises a plurality of humidity sensors, the controller being configured to not stop operation of the compressor if the measured humidity levels from all of the humidity sensors are not less than the threshold humidity level.

In yet another aspect of the invention, the plurality of humidity sensors are spaced along a windshield of the automotive vehicle.

Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a climate control system embodying the principles of the present invention; and

FIG. 2 is a flowchart illustrating a method of operating the climate control system illustrated in FIG. 1 in accordance with the principles of the present invention.

DETAILED DESCRIPTION

Referring now to the drawings, an HVAC or climate control system embodying the principles of the present invention is illustrated therein and designated at 10. The climate control system 10 generally resides behind an instrument panel (not shown) that is located in the interior cabin of the automotive vehicle, generally immediately below the front windshield 12. In at least one mode of operation, the climate control system 10 directs air towards the interior surface of the windshield 12 and may, additionally, direct air towards an interior surface of a side window 14, such as the driver's side window shown in FIG. 1. When used herein, the term “window” is intended to be generic for either the windshield 12 or the side window 14. As such, the latter terms are interchangeable or alternative considerations. If the context of the text is meant to connote a specific interpretation, the terms windshield 12 and side window 14 are employed.

In order to direct air towards the window, the climate control system 10 includes one or more vents 16 located near the window. The vents 16 are positioned such that when air is provided by a blower 18, the air is directed by the vent 16 out and onto the interior surface of the window. Air being discharged by the vent 16 is generally designated at 20.

The blower 18 is controlled by an electronic control unit (ECU) 22 of the climate control system 10. The ECU 22 is additionally coupled to a user interface 24, provided on part of the instrument panel, and which includes various inputs for operating the climate control system 10. Some of these inputs, but by no means an exhaustive illustration thereof, are seen in FIG. 1. At least one of these inputs allows for the selection of a mode within which the climate control system 10 will operate.

The mode for operation of the climate control system 10 may be made by way of a general mode selection button 26 that allows for the switching between or sequencing through a number of different modes. Alternatively or additionally, the user interface 24 may include one or more designated mode buttons 28. As seen in FIG. 1, user interface 24 includes a designated mode button 28 for selection of the defrost mode of the climate control system 10, as well as a general mode selection button 26.

The ECU 22 is also coupled to one or more humidity sensors 30. If a single humidity sensor 30 is employed, the sensor 30 is preferably positioned in a location adjacent to the interior surface of the windshield 12. If multiple humidity sensors 30 are employed, more than one humidity sensor 30 may be located adjacent to the windshield 12 and/or an additional humidity sensor 30 may be located adjacent to the side window 14. In locating the humidity sensors 30 adjacent to the windshield 12 and side window 14, the humidity sensors 30 may be mounted directly to the interior surface of these windows or may be mounted to a trim component located adjacent to these windows. With either configuration, the humidity sensors 30 are mounted such that they are not directly positioned in front of the vents 16. In other words, the air 20 being discharged from the vents 16 should not be directed directly at or over the humidity sensors 30. In this way, the humidity sensors 30 are capable of providing to the ECU 22 a measured value (H_(m)) for the humidity of the ambient air in the region adjacent to the windows without undue influence from the air being discharged from the vents 16.

Air from the blower 18 is routed by a conduit 32 such that the air passes over the chilled or cooler surfaces of a condenser (a heat exchanger) coupled to a compressor, which are collectively designated at 34 in FIG. 1, of the air conditioning subsystem of the climate control system 10. From the condenser 34, the air is directed by the conduit 32 to a heater core 36 (also a heat exchanger) of the heating subsystem of the climate control system 10. Typically, the heater core 36 is coupled to the coolant system of the vehicle's engine and uses heat derived from the engine to warm the air as it passes over the surfaces of the heater core 36. From the heater core 36, the warmed air is directed to the vents 16 and discharged at 20 toward the interior surface of the windshield 12.

When it is desired that air being provided to the cabin be dehumidified, the air conditioning subsystem of the climate control system 10 is operated, resulting in operation of the compressor 34 and cooling of fluid passing through the condenser 34, and thereby cooling of the surfaces of the condenser 34 itself. If the relative humidity in the air is sufficiently high as it passes over the condenser 34, the water vapor in the air will condense on the surfaces of the condenser 34, thereby resulting in less humid air being passed from the condenser 34 to the heater core 36 and discharged into the cabin of the vehicle. With drier air 20 being directed at the interior surface of the window during the defrost mode of operation, the likelihood that the window will become fogged is decreased.

In theory, the compressor 34 can be continuously run to remove excess water vapor from the air in the cabin compartment of the vehicle. As previously noted, however, when operating the compressor 34, the vehicle's power consumption is increased while fuel economy and mileage range are decreased. For this reason, most climate control systems do not operate the compressor in all modes of operation. Typically, the compressor 34 will be run by the climate control system in the air-conditioning mode and, surprisingly to many people, in the defrost mode. The compressor 34 is operated during the defrost mode in order to dry the air being provided to the window and thereby prevent or minimize fogging of the window.

In the present climate control system 10, if the defrost mode has been selected, either by using the general mode selection button 26 or the designated defrost mode button 28, the system makes a determination as to whether the compressor 34 is running and, if so, if it should be kept running The method of operating the climate control system 10 is set out in FIG. 2. If operation of the compressor 34 is not needed because the relative humidity of the air adjacent to the window is not likely to cause fogging, the compressor 34 is turned OFF. This directly results in increased available power to the vehicle, better fuel economy and mileage range.

Referring now to FIG. 2, generally the climate control system 10 operates to determine if the humidity of the air near the window is high enough to promote fogging. In doing this, a measured humidity level is compared against a threshold humidity level. The threshold humidity level is the humidity level at which water vapor in the air will condense if warmed and brought into contact with the cooler window. This threshold may be dynamically determined based on ambient conditions or it may be static and based on average conditions as to when the defrost mode might be employed. If the measured humidity is less than the threshold, the system 10 then determines if the compressor 34 is running If it is running, the system 10 turns OFF the compressor 34, increasing the efficiency of the operation of the vehicle.

Operation of the system 10 begins in step 50. After beginning, the ECU 22 determines in step 52 whether the climate control system 10 is being operated in the defrost mode. As noted above, the system 10 enters the defrost mode by a person in the vehicle manually selecting the mode via the designated defrost mode button 28 or general mode selection button 26. Alternatively, the system 10 may enter the defrost mode automatically because of various sensed parameters.

If the system 10 is not in the defrost mode, then the procedure proceeds to box 60, returns to box 50 and starts over. If the system 10 determines in step 52 that it is in the defrost mode, the method proceeds to step 54.

In step 54, the ECU 22 determines if the humidity level in the vicinity of the windshield 12 is less than a threshold humidity level (H_(t)). The measured humidity level (H_(m)) is determined by the humidity sensors 30, which are in communication with the ECU 22. If only a single humidity sensor 30 is used in the system 10, the ECU 22 compares that measured value with the threshold humidity level (H_(t)). If more than one humidity sensor 30 is used, the ECU 22 determines if all of the measured humidity levels (H_(m)) are below the threshold humidity level (H_(t)). If it is determined that the measured humidity level (H_(m)) is not less than the threshold humidity level (H_(t)), the method proceeds to box 62.

In box 62, the ECU 22 determines if the compressor 34 is ON. If the compressor 34 is ON, the process proceeds to box 60 and restarts. If the compressor 34 is not ON, in other words, the compressor 34 is OFF, the process proceeds to box 64. In box 64, the ECU 22 turns the compressor 34 ON then proceeds to box 60 and restarts the process.

If, in box 54, the ECU 22 determines that the measured humidity level (H_(m)) is less than the threshold humidity level (H_(t)), the process then proceeds to box 56. It should be noted that, if more than one humidity sensor 30 is being employed in the system 10, then all of the measured humidity levels (H_(m)) should be less than the threshold humidity level (H_(t)).

In box 56, the ECU 22 determines if the compressor 34 is ON. If the ECU 22 determines that the compressor 34 is OFF (not ON), the method proceeds to box 60 and returns to start. If the compressor 34 is determined by the ECU 22 to be ON, then the method proceeds to box 58, wherein the compressor 34 is turned OFF because the need for drier air to prevent fogging either does not exist or has been abated.

As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from the spirit of this invention, as defined in the following claims. 

I/we claim:
 1. A climate control system for the interior cabin of an automotive vehicle, the climate control system comprising: a mode selection device configured for selecting between a defrost mode and at least one non-defrost mode; a compressor and condenser configured to dehumidify air being provided to an interior cabin of the automotive vehicle; a humidity sensor located adjacent to a window of the automotive vehicle; a controller coupled to the mode input device, the compressor and condenser, and to the humidity sensor; a blower configured to move air over the condenser in providing air to the cabin of the automotive vehicle; and wherein, when the mode selection device is in the defrost mode, the controller being configured to receive a humidity signal from the humidity sensor indicative of the humidity in the vicinity of the window and being configured to operate a compressor if the humidity is above a threshold value and to not operate the compressor if the humidity is below the threshold value.
 2. The climate control system of claim 1, wherein the window is a windshield of the automotive vehicle.
 3. The climate control system of claim 1, wherein the window is a side window of the automotive vehicle.
 4. The climate control system of claim 1, further comprising two humidity sensors and wherein the controller is configured to operate the compressor if the humidity signal from at least one of the two humidity sensors is greater than the threshold value and is configured to not operate the compressor if the humidity signals from all of the humidity sensors are below the threshold value.
 5. The climate control system of claim 1, further comprising an air vent located adjacent to the window and coupled to direct air from the blower onto the window.
 6. The climate control system of claim 5, wherein the humidity sensor is spaced apart from the vent.
 7. The climate control system of claim 1 wherein the humidity sensor is located adjacent to a lower portion of the window.
 8. A method of operating a climate control system of an automotive vehicle, the method comprising the steps of: measuring the humidity of air in a vicinity of a window of the automotive vehicle; determining if the climate control system is in a defrost mode; providing a flow of air specifically directed toward the window when the climate control system is in the defrost mode; measuring the humidity of air in the vicinity of the window; comparing the measured humidity with a threshold humidity value; determining if a compressor coupled to a condenser provided as part of an air conditioning subsystem is operating; and if the compressor is operating, turning OFF the compressor when the measured humidity is less than the threshold humidity value.
 9. The method of claim 8, further comprising the step of measuring the humidity of air in two locations within the vicinity of the window.
 10. The method of claim 9, wherein if the measured humidity at one of the two locations is above the threshold humidity value, the compressor is not turned OFF.
 11. The method of claim 9, wherein if the measured humidity at both of the two locations is below the threshold humidity value, the compressor is turned OFF.
 12. The method of claim 8, further comprising the step of heating the flow of air.
 13. A climate control system for the interior cabin of an automotive vehicle, the climate control system comprising: a defrost mode selection device provided as part of a user interface and being selectable to enter a defrost operational mode of the climate control system; a compressor and a condenser configured to dehumidify a flow of air being provided to an interior cabin of the automotive vehicle, the condenser being located within the flow of air; at least one humidity sensor located adjacent to a window of the automotive vehicle and configured to provide a measured humidity signal indicative of a measured humidity level; a controller coupled to the defrost mode input device, the at least one humidity sensor, and the compressor and condenser; a blower configured to move air over the condenser when providing the flow of air to the cabin of the automotive vehicle; and wherein, when the defrost mode selection device is selected, the controller being configured to receive the measured humidity signal from the at least one humidity sensor and being configured compare the measured humidity level to a threshold humidity level, wherein the controller is configured to stop operation of the compressor if the measured humidity level is less than the threshold humidity level.
 14. The climate control system of claim 13, wherein the window is one of a windshield and a side window of the automotive vehicle.
 15. The climate control system of claim 13, wherein the controller is configured to continue operation of the compressor if the measured humidity level is greater than the threshold humidity level.
 16. The climate control system of claim 13, further comprising a plurality of humidity sensors, the controller being configured to stop operation of the compressor if the measured humidity levels from all of the humidity sensors are less than the threshold humidity level.
 17. The climate control system of claim 13, further comprising a plurality of humidity sensors, the controller being configured to not stop operation of the compressor if the measured humidity levels from all of the humidity sensors are not less than the threshold humidity level.
 18. The climate control system of claim 17, wherein the plurality of humidity sensors is spaced along a windshield of the automotive vehicle. 